The present invention relates to LSI cooling apparatuses having various structures used in electronic devices such as computer systems and in particular to LSI cooling apparatuses suitable to cooling of LSIs having high heat generating densities.
As for cooling (air cooling) of LSIs in the past, they could be cooled by a simple structure mainly comprising a flat board because the heat generating density was several W/cm.sup.2 or less at most. As the heat generated by LSIs increases in recent years, it has become necessary to pursue heat sink structures which are excellent in cooling performance. Among them, a heat sink structure taking the shape of pin fin is considered to be a desirable structure from the view point of advantages in mounting and improvement in heat radiation performance. An example using this structure is described on page 87 of Nikkei Electronics, Oct. 30, 1989. This pin fin structure itself is already known as a conventional technique. For largely improving the cooling performance, however, selection of dimension specifications of individual pins becomes extremely important. In the range of the prior art, however, there is a limitation in manufacturing and study of cooling performance is not sufficient. In this context, pins each having a diameter of 1 mm.phi. are used in most cases and flow of cooling air is not considered.
The heat sink structure of pin fin type has an advantage in that there are no restrictions upon the direction of cooling wind and another advantage of typically higher heat transfer performance (as compared with the flat board type). In case it is attempted to make full use of those advantages, however, an optimum structure design based upon a heat transfer phenomenon peculiar to the heat sink of pin fin type is demanded. That is to say, in a pin fin structure, not only the flow state but also the heat transfer characteristics change according to the pin diameter and the velocity of cooling air. Because of these phenomena, there exists a range of dimension specifications suitable for LSI cooling which is the subject of the present invention. In the prior art, however, the above described points are not considered.